image: This is a male green honeycreeper (Chlorophanes spiza). view more
Credit: Cagan H. Sekercioglu
A study suggests that despite the decline in Costa Rican bird populations, agricultural sites may have some conservation benefits. Tropical agriculture contributes to biodiversity loss, but agricultural sites may become habitats for various species. Cagan H. Sekercioglu, Gretchen C. Daily, and colleagues mist-netted 57,255 birds of 265 species in Costa Rica between 1999 and 2010. The birds came from 19 sites, including forests and coffee plantations. Overall, more bird populations were declining than were stable or increasing. Insectivores suffered the greatest declines. Compared with forests, coffee plantations had higher ratios of immature and juvenile birds to adult birds for nonmigratory species. Although 49% of species preferred forests to coffee plantations, 39% of species preferred coffee plantations and 12% of species used both habitats. Compared with coffee plantations exhibiting less tree cover, plantations that were more shaded exhibited increases in species that were forest-dependent, range-restricted, and of conservation concern. Wintering migratory birds also preferred shaded coffee plantations over forests. Population declines were greater in the 250 ha Las Cruces forest than in 3-5 ha forest fragments. The findings suggest that large protected forest areas are important for forest bird conservation. Moreover, coffee plantations may be an important habitat for migratory birds, some forest-dependent birds, and young birds unable to find forest territories, according to the authors.
Article #18-02732: "Long-term declines in bird populations in tropical agricultural countryside," by Cagan H. Sekercioglu et al.
MEDIA CONTACT: Gretchen C. Daily, Stanford University, CA; email: gdaily@stanford.edu; Cagan H. Sekercioglu, University of Utah, Salt Lake City, UT; tel: 385-549-5454; email: c.s@utah.edu
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Journal
Proceedings of the National Academy of Sciences